It is known in automobile fuel systems to provide a pressure regulating relief valve in the fuel line, with the valve being designed to open at a specified pressure to allow fuel to drain from the fuel line back to the fuel tank. Relief back to the fuel tank is used under several conditions. It is known to use fuel pumps that deliver much higher fuel flow rates to the fuel rail than is required by the engine for combustion, particularly at low speed operation but also even at high speed operation. For example, it is known to use pumps that deliver 50 to 80 liters/minute, and to bleed off some of the fuel flow even while the engine operates. A pressure regulator/relief valve is used to direct the excess fuel flow back to the fuel tank. Another use of a pressure regulator/control valve is when the engine has been turned off, and heat radiating from the engine causes a significant temperature rise in the fuel rail. Under these conditions, the fuel remaining in the fuel rail or in other fuel system components is heated. As the temperature of the fuel rises, pressure in the fuel system also increases. Accordingly, even with the engine turned off, it is known to have the pressure regulator/relief valves open if the pressure increases to a pre-determined level, thereby allowing fuel and vapor to drain back to the fuel tank. Fore example, it is known to have the valves open at approximately 60 psi+/−about 7 psi.
In a known relief valve, an outer plastic cup houses a metal regulator valve that includes two O-rings and a plastic filter. The valve is pressed into a seat area in the plastic cup and is held in place by a metal u-clip. The valve has three tubing connections. Two of the connections are used to install the valve as an in-line component at some location in the fuel delivery path. With the valve closed, fuel flows through the two in-line connections. A third connection communicates with the fuel tank interior. Under the prescribed high pressure condition for which the valve is designed, the valve opens to divert at least some fluid flow through the third connection back to the fuel tank.
Known pressure regulating control valves used for this purpose are relatively complicated, expensive to manufacture and assemble, large and relatively heavy for the environment in which they are used. Control valves of this type are known to be unique to particular applications; and to provide valves of different types for different installations and uses, such as valves operating under different pressure conditions, it has been necessary to stock a large variety of different valves and the parts therefor.
Accordingly, it would be desirable to provide an improved pressure regulating control valve that is simple in operation, small, lighter in weight and easier to assemble and install. It is desirable also to provide a pressure regulating relief valve that can be readily and easily assembled to operate under different pressure conditions so that fewer different valves and/or parts for valves are necessary to assemble valves for operating under different conditions.